1. Field of the Invention
The invention relates to a device for detecting a quantity while receiving and/or discharging a fluid having a gas portion, in particular milk or fuel, having a measurement line for conducting the fluid, a flow measuring unit for the fluid, which is in fluid connection with the measurement line, a degree of filling measuring unit for the fluid, which is in fluid connection with the measurement line and which comprises an electrode arrangement for determining electrical properties of the fluid present in the measurement line, and an evaluation unit for determining the fluid amount conveyed through the measurement line and which is in a signal connection with the degree of filling measuring unit and the flow measuring unit. Such a device is designed with a measurement line for conducting through the fluid, a flow measuring unit for the fluid, which is in fluid connection with the measurement line, a degree of filling measuring unit for the fluid, which is in fluid connection with the measurement line and comprises an electrode arrangement for determining electrical properties of the fluid present in the measurement line, and an evaluation unit for determining the amount of fluid conveyed through the measurement line, which evaluation unit is in a signal connection with the degree of filling measuring unit and the flow measuring unit.
The invention further relates to a method for detecting the quantity of a fluid with a gas portion, for example milk or fuel, flowing in a measurement line, in which a degree of filling measurement is carried out in the measurement line by means of a degree of filling measuring unit, a flow measurement is carried out in the measurement line by means of a flow measuring unit, and the amount of fluid conveyed is calculated from the results of the flow measurement and those of the degree of filling measurement. It is provided in the method that a degree of filling measurement is carried out in the measurement line by means of a degree of filling measuring unit, a flow measurement is carried out in the measurement line by means of a flow measuring unit and the amount of fluid conveyed is calculated from the results of the flow measurement and those of the degree of filling measurement.
2. Description of Related Art Including Information Disclosed Under 37 CFR §§1.97 and 1.98
A generic device and a generic method are known for example from DE 10 2005 005 295 A1. This printed publication teaches the implementation of a flow measurement on the measurement and conveying line through which the fluid is conducted in order to detect the amount conveyed. In order to be able to provide exact measurement results even if there are gas pockets in the fluid, a degree of filling measurement is additionally carried out on the measurement line, that is to say the fluid content is determined in the line cross-section, whereby this content results from the overall cross-section less the gas content. The resulting measurement results are used to compensate the results of the flow measurement. A capacitance measurement or a conductibility measurement can be provided according to DE 10 2005 005 295 A1 in order to measure the degree of filling.
DE 101 56 450 A1 discloses a method and a device for determining a mass flow of milk flowing during a milking process. It is described in this printed publication that a capacitance or a characteristic value proportional thereto is determined in the measurement volume, the capacitance is compared with previously known capacitances, the speed of the milk flow is determined and a milk flow is determined from the aforementioned data.
DE 195 40 884 C2 and EP 0 855 576 A1 disclose methods and installations for measuring the volume of flowing fluids, thereby avoiding measurement errors caused by inadmissibly high gas portions. In accordance with the teaching of these printed publications, a degassing container is provided in the line system upstream of a volume meter, in which degassing container gas portions are to be separated, so that they do not influence the volume measurement. Furthermore an optical gas bubble sensor is provided. If the value measured by the gas bubble sensor exceeds an admissible value, from which a reliable gas separation may no longer be possible, a corresponding control is carried out, for example by adjusting valves, in order to modify the fluid flow until the admissible value is reached again or the actual value falls short of this admissible value. Particularly by reason of the required gas separator, however, such installations can be comparatively expensive and have a comparatively high weight and a high space requirement.
A further measuring unit for a fluid flow is known from DE 691 21 181 T2. It is provided herein that the homogeneity of the liquid is measured and for the purpose of degassing a valve is closed in the flow system if the inhomogeneity caused by the gas content exceeds a threshold value.
A further measurement method for fluids is known from DE 197 33 715 C1, in which the discharged amount is measured by means of a volume meter and the discharge is interrupted if the gas portion exceeds a certain value.
Insofar as, as known in particular from DE 10 2005 005 295 A1, gas portions are not separated and are instead tolerated in the flow measurement, detected in the measurement and used to determine the amount conveyed, undesirable interruptions in the product flow in case of gas loads can generally be avoided and a gas separator is not necessary. In comparison with measuring units with gas separators, a considerable simplification in the construction and a dramatic weight reduction are hereby achieved. Furthermore, a particularly rapid discharge is possible and also the removal of the remains from the installation is considerably simplified, as no high volume gas separator needs to be emptied. However, in particular the calibration regulations place high requirements upon the precision of the degree of filling measurement, as the results of this measurement are incorporated directly into the measurement result for the amount conveyed.